James C. A. Whetter (born 1935 at St Austell, Cornwall, UK) is a noted Cornish historian and editor of The Cornish Banner (An Baner Kernewek).
Whetter's books include The History of Glasney College (Padstow: Tabb House, 1988); Cornwall in the Seventeenth Century (Padstow: Lodenek Press, 1974); and The History of Falmouth (Redruth: Dyllansow Truran, 1981). In 1974, he stood twice as the Mebyon Kernow parliamentary candidate before founding, in 1975, the Cornish Nationalist Party, a political party which split from Mebyon Kernow to campaign for Cornish independence.
The Roseland Institute contains a library of over 20,000 books in the process of being catalogued and put on-line and is the base for the publishing activities of Lyfrow Trelyspen and CNP Publications. The former produces works on Cornish history, essays and related subjects. The latter, the quarterly Cornish magazine, The Cornish Banner (An Baner Kernewek).